Economic disparities in school readiness and early academic achievement have been well-documented and are the focus of numerous policies and interventions. Children from low-income households tend to enter kindergarten with fewer of the academic skills that are important for school success. These differences endure and are even exacerbated as children progress through school. Increasing evidence suggests that economic conditions in early childhood are especially important for shaping children's academic trajectories. The present study will examine whether children's early experiences in their home environments and child care settings explain associations between early childhood income and achievement trajectories through elementary school. Furthermore, it will consider whether instructional practices in elementary school classrooms attenuate or exacerbate the association between early childhood income and achievement trajectories. The proposed study will make an innovative contribution to the literature by focusing on proximal processes taking place in early home, child care, and elementary school classrooms, while simultaneously taking into account more ecologically distal characteristics of children's home and educational environments. Another unique contribution is linking early childhood income to trajectories of academic achievement. The present study will focus specifically on key proximal parenting, child care, and classroom practices. Accumulating evidence has illustrated that home environments that are cognitively stimulating, sensitive, and responsive enhance school readiness skills and academic achievement. High quality child care, characterized by many of these same home dimensions, promotes academic skills as well. In addition, increasing evidence suggests that both the amount and the type of classroom instruction that children experience are important for academic success during the early elementary school years. To address our research aims, we will employ a large, multi-site, longitudinal dataset that is renowned for its breadth and depth in child, family, child care, and classroom measures: the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development (NICHD SECCYD). Unlike other large national surveys, this data set is unique in its collection of high quality, multi-method measurement from numerous reporters on a wide range of proximal processes in multiple contexts. The present study will have broader impacts on public policies and programs that aim to improve the educational and economic prospects for low-income children because it will strengthen our understanding of the sources of economic disparities in academic achievement trajectories. These early academic achievement trajectories lay the foundation for later school success, educational attainment, and well-being into adulthood. Moreover, it will consider how instructional practices in elementary school classrooms attenuate or exacerbate the association between early childhood income and achievement trajectories.